Is this worth the money? – GreenBuildingAdvisor

I have a large 2nd floor Master with a double gable vaulted ceiling. The interior ceiling is beautiful wood that I want to keep intact. I’m about to start a small dormer construction project that includes reroofing the entire west facing roof. Presently, this 2^nd floor room suffers from high radiant heat temperatures and that’s something I would like to cure. I considering creating a hot roof from the exterior by removing the roof sheathing and filling the 2×10 joist bays with closed cell foam insulation. I’m in Zone 5. Is this my best option? I’m not sure this will do much to solve my heat problem, as the joists will still be connected to the roof deck and will transmit heat to the wood ceiling. To the best of my knowledge, the roof is currently insulated with R30 fiberglass batt.